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Extensive Study of the Quality of Fission Yields from Experiment, Evaluation and GEF for Antineutrino Studies and Applications
No full textInternational audienceThe understanding of the antineutrino production in fission and the theoretical calculation of the antineutrino energy spectra in different, also future, types of fission reactors rely on the application of the summation method, where the individual contributions from the different radioactive nuclides that undergo a beta decay are estimated and summed up. The most accurate estimation of the independent fission-product yields is essential to this calculation. This is a complex task because the yields depend on the fissioning nucleus and on the energy spectrum of the incident neutrons.In the present contribution, the quality of different sources of information on the fission yields is investigated, and the benefit of a combined analysis is demonstrated. The influence on antineutrino predictions is discussed.In a systematic comparison, the quality of fission-product yields emerging from different experimental techniques is analyzed. The traditional radiochemical method, which is almost exclusively used for evaluations, provides an unambiguous identification in Z and A , but it is restricted to a limited number of suitable targets, is slow, and the accuracy suffers from uncertainties in the spectroscopic nuclear properties. Experiments with powerful spectrometers, for example at LOHENGRIN, provide very accurate mass yields and a Z resolution for light fission products from thermal-neutron-induced fission of a few suitable target nuclei.On the theoretical side, the general fission model GEF has been developed. It combines a few general theorems, rules and ideas with empirical knowledge. GEF covers almost all fission observables and is able to reproduce measured data with high accuracy while having remarkable predictive power by establishing and exploiting unexpected systematics and hidden regularities in the fission observables. In this article, we have coupled for the first time the GEF predictions for the fission yields to fission-product beta-decay data in a summation calculation of reactor antineutrino energy spectra. The first comparisons performed between the spectra from GEF and those obtained with the evaluated nuclear databases exhibited large discrepancies that highlighted the exigency of the modelisation of the antineutrino spectra and showing their usefulness in the evaluation of nuclear data. Additional constraints for the GEF model were thus needed in order to reach the level of accuracy required by the antineutrino energy spectra. The combination of a careful study of the independent isotopic yields and the adjunction of the LOHENGRIN fission-yield data as additional constraints led to a substantially improved agreement between the antineutrino spectra computed with GEF and with the evaluated data. The comparison of inverse beta-decay yields computed with GEF with those measured by the Daya Bay experiment shows the excellent level of predictiveness of the GEF model for the fundamental or applied antineutrino physics.The main results of this study are: – an improved agreement between the antineutrino energy spectra obtained with the newly tuned GEF model and the JEFF-3.1.1 and JEFF-3.3 fission yields for the four main contributors to fission in standard power reactors; – indications for shortcomings of mass yields for 241 Pu(n th , f) and other systems in current evaluations; – a demonstration of the benefit from cross-checking the results of different experimental approaches and GEF for improving the quality of nuclear data; – an analysis of the sources of uncertainties and erroneous results from different experimental approaches; – the capacity of GEF for predicting the fission yields (and other observables) in cases (in terms of fissioning systems and excitation energies) which are presently not accessible to experiment; – predictions of antineutrino energy spectra that aim to assess the prospects for reactor monitoring, and based on the GEF fission yields associated with the beta-decay data of the most recent summation model
The KM3NeT potential for the next core-collapse supernova observation with neutrinos
No full textInternational audienceThe KM3NeT research infrastructure is under construction in the Mediterranean Sea. It consists of two water Cherenkov neutrino detectors, ARCA and ORCA, aimed at neutrino astrophysics and oscillation research, respectively. Instrumenting a large volume of sea water with optical modules comprising a total of photomultiplier tubes, KM3NeT will achieve sensitivity to neutrinos from Galactic and near-Galactic core-collapse supernovae through the observation of coincident hits in photomultipliers above the background. In this paper, the sensitivity of KM3NeT to a supernova explosion is estimated from detailed analyses of background data from the first KM3NeT detection units and simulations of the neutrino signal. The KM3NeT observational horizon (for a discovery) covers essentially the Milky-Way and for the most optimistic model, extends to the Small Magellanic Cloud (). Detailed studies of the time profile of the neutrino signal allow assessment of the KM3NeT capability to determine the arrival time of the neutrino burst with a few milliseconds precision for sources up to 5–8 kpc away, and detecting the peculiar signature of the standing accretion shock instability if the core-collapse supernova explosion happens closer than 3–5 kpc, depending on the progenitor mass. KM3NeT’s capability to measure the neutrino flux spectral parameters is also presented
The novel Mechanical Ventilator Milano for the COVID-19 pandemic
No full textInternational audienceThis paper presents the Mechanical Ventilator Milano (MVM), a novel intensive therapy mechanical ventilator designed for rapid, large-scale, low-cost production for the COVID-19 pandemic. Free of moving mechanical parts and requiring only a source of compressed oxygen and medical air to operate, the MVM is designed to support the long-term invasive ventilation often required for COVID-19 patients and operates in pressure-regulated ventilation modes, which minimize the risk of furthering lung trauma. The MVM was extensively tested against ISO standards in the laboratory using a breathing simulator, with good agreement between input and measured breathing parameters and performing correctly in response to fault conditions and stability tests. The MVM has obtained Emergency Use Authorization by U.S. Food and Drug Administration (FDA) for use in healthcare settings during the COVID-19 pandemic and Health Canada Medical Device Authorization for Importation or Sale, under Interim Order for Use in Relation to COVID-19. Following these certifications, mass production is ongoing and distribution is under way in several countries. The MVM was designed, tested, prepared for certification, and mass produced in the space of a few months by a unique collaboration of respiratory healthcare professionals and experimental physicists, working with industrial partners, and is an excellent ventilator candidate for this pandemic anywhere in the worl
Speciation, solubility and complexation of Neptunium (V) under radiolysis in Hydroxyl media
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Measurement of the production cross section of prompt baryons at midrapidity in pp collisions at = 5.02 TeV
No full textInternational audienceThe transverse momentum (p) differential cross section of the charm-strange baryon is measured at midrapidity (|y| < 0.5) via its semileptonic decay into eΞν in pp collisions at = 5.02 TeV with the ALICE detector at the LHC. The ratio of the p-differential -baryon and D-meson production cross sections is also reported. The measurements are compared with simulations with different tunes of the PYTHIA 8 event generator, with predictions from a statistical hadronisation model (SHM) with a largely augmented set of charm-baryon states beyond the current lists of the Particle Data Group, and with models including hadronisation via quark coalescence. The p-integrated cross section of prompt -baryon production at midrapidity is also reported, which is used to calculate the baryon-to-meson ratio /D = 0.20 ± 0.04 (syst.). These results provide an additional indication of a modification of the charm fragmentation from ee and ep collisions to pp collisions.[graphic not available: see fulltext
Analyses à l'aide de PIXE à haute énergie, de pièces d'argent et de matrices de sceaux en cuivre, provenant des collections du musée Dobrée (France, XIIIe -XIXe siècle)
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Section efficace de production de rayons X de la couche K : qu'en est-il à haute energie ?
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Impact of hadronisation process and hadronic cascades on the 2 nd order net-charge cumulants studied through the BES with EPOS 4
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Les Radionucléides dans l'environnement. Enjeux sociétaux et défis scientifiques.
No full texthttps://new.societechimiquedefrance.fr/numero/n460-461-mars-avril-2021/International audienceLes recherches sur le comportement des radionucléides naturels et artificiels (RN) dans l'environnement visent à évaluer, prévoir ou réduire leurs transferts et effets dans les milieux naturels (en lien avec leur spéciation), et recoupent des enjeux sociétaux : sureté des futurs sites de stockage des déchets radioactifs, gestion de sites à radioactivité naturelle renforcée. Dans ce contexte, la communauté académique se positionne sur la recherche amont autour de grandes questions (base de données sur la chimie des RN en solution et aux interfaces, évaluation des effets des faibles doses, procédés de remédiation) et de questions transverses (modélisation, instrumentation de pointe). Des défis pour le futur sont de développer des études multi-échelles et interdisciplinaires, ce qui est illustré dans cet article par des études du devenir des RN sur le site d'une ancienne mine d'uranium (Rophin, Puy-de-Dôme) et du rôle des matières organiques naturelles. Mots-clés Radionucléides, environnement, spéciation, effets, interdisciplinarité
Procédé et système de suivi d’un faisceau d’hadrons pendant un traitement d’hadronthérapie d’un sujet
No full textCopropriétaires : CNRS, Institut Mines TélécomDate de dépôt : 18/10/2019N° de dépôt : FR191170